Carbonated beverages, such as beer, contain carbon dioxide gas which is dissolved in solution. This dissolved carbon dioxide gas affects the flavor profile of the beverage and also causes the characteristic foaming or "outgassing" during dispensing of the beverage.
Some types of beers are commonly charged with nitrogen gas in place of, or in addition to, carbon dioxide gas. Beer that has been charged with nitrogen gas in this manner is commonly referred to as "nitrogenized beer" or, more simply, "nitro beer". It is to be understood that the term "beer", as used herein, is intended to include various fermented beverages, including, but not limited to, those commonly referred to as "stout", "ale", "lager" and even "cider".
The use of nitrogen gas in beer causes the beer to display a more creamy head of foam, or froth, upon dispensing than would a beer containing only carbon dioxide gas in solution. The use of nitrogen gas also improves "lacing" which is the feature of foam coating the inside of the glass from which the beer is consumed. Both the provision of a creamy head and improved lacing are important considerations to consumers and are, therefore, of commercial importance. Typical nitro beers contain dissolved nitrogen at a concentration of at least about 30 ppm.
In order to achieve these desired effects in a nitro beer, it is necessary that the dissolved nitrogen gas be forced out of solution during dispensing, i.e., immediately prior to the time at which the beer is consumed by a consumer. This process, often referred to as gas evolution or gas liberation, occurs when a large number of relatively small gas bubbles form within the liquid beer. These gas bubbles, in turn, result in the improved froth and lacing characteristics discussed above. The use of nitrogen gas provides better froth and lacing characteristics, relative to carbon dioxide gas, because the gas bubbles liberated by dissolved nitrogen are much smaller than those liberated by dissolved carbon dioxide.
Compared to carbon dioxide, nitrogen is relatively difficult to force out of solution. Accordingly, specialized beer taps or faucets traditionally have been used for dispensing nitro beers from pressurized dispensing systems, such as those used in bars and restaurants. These specialized faucets typically include a plurality of small openings through which the beer is forced during dispensing. These holes are typically formed as cylindrical through-holes each of which may, for example, have a cross-sectional area of about 0.00062 square inch.
The pressurized dispensing system to which such a faucet is connected typically operates at a relatively high pressure, in the range of from about 30 to about 40 psi. Forcing the nitro beer through these small openings at such a relatively high pressure agitates the beer sufficiently to drive a substantial amount of nitrogen out of solution and, thus, produce the desirable characteristics described above.
In more recent years, efforts have also been made to package nitro beers in containers such as cans and bottles. In order to produce the necessary gas liberation in such containers, agitation devices have been developed which can be placed within the containers and activated upon opening of the containers. These agitation devices are commonly referred to in the industry as "smoothifiers" or "widgets". An example of such a device is described in U.S. Pat. No. 4,832,968 to Forage et al. which is hereby incorporated by reference for all that is disclosed therein.
It has been found that the specialized faucets described above will not function properly in dispensing nitro beer from a relatively low pressure dispensing system, i.e., one that operates at a pressure less than about 30 psi. Although nitro beer will dispense through the specialized faucet at this pressure, insufficient nitrogen gas is liberated and the desirable froth and lacing characteristics described above are not achieved. One type of such a relatively low pressure dispensing system is a self-contained system in which a flexible pressure pouch is immersed within a container of beer. The pressure pouch may comprise various compartments housing components of a two-part gas generating system. The pressure pouch may be configured such that, as beer is dispensed from the system, additional chemical compounds are mixed, thus causing the pressure pouch to expand and maintain the pressure within the system. Examples of such dispensing systems, and of pressure pouches used in conjunction therewith, are disclosed in U.S. Pat. No. 4,919,310 to Young et al.; U.S. Pat. No. 4,923,095 to Dorfman et al.; U.S. Pat. No. 5,333,763 to Lane et al.; U.S. Pat. No. 5,769,282 to Lane et al.; and U.S. patent application Ser. No. 09/002,406, filed Jan. 2, 1998 of Lane et al. for MULTI-COMPARTMENT POUCH HAVING A FRANGIBLE COMPARTMENT DIVIDER, which are all hereby specifically incorporated by reference for all that is disclosed therein.
Such relatively low pressure dispensing systems may operate generally within a pressure range of between about 15 and about 25 psi. As described above, conventional nitro beer faucets will not operate adequately in such a low pressure environment.
It has also been found that the small through-holes commonly used in conventional nitro beer faucets are difficult and expensive to manufacture. This is a particular problem when it is desired to dispense nitro beer from a disposable system, rather than a fixed beer dispensing faucet such as might be found in a bar or pub.
Accordingly, it would be desirable to provide a dispensing mechanism which provides for the proper dispensing of nitrogenized beverages from a relatively low-pressure dispensing system and which overcomes the manufacturability problems associated with small through holes as discussed above.